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  • Copernicus GmbH  (23)
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  • Copernicus GmbH  (23)
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  • 1
    In: Annales Geophysicae, Copernicus GmbH, Vol. 23, No. 8 ( 2005-11-08), p. 2943-2951
    Abstract: Abstract. Ground-based observations can be used to provide substantial support for Cluster/Double Star measurements and greatly enhance the mission's scientific return. There are six Chinese ground stations involved in coordinated cluster/Double Star and ground-based instrument observations. Among them, the Chinese Zhongshan Station in Antarctica and the Yellow River Station on Svalbard are closely magnetic conjugate and are situated under the ionospheric projection of the magnetospheric cusp regions, which, combined with satellite data, provide a perfect configuration to conduct conjugate studies of cusp phenomena. In this paper we present the ground-based instrumentation at these stations, discuss the restriction which is applyed to the optical sites and present an overview of the occurrences for conjunctions of these instruments with the spacecraft. Samples of data products are given to illustrate the potential use of these instrumentations in coordination with Cluster/Double Star measurements.
    Type of Medium: Online Resource
    ISSN: 1432-0576
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2005
    detail.hit.zdb_id: 1458425-6
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  • 2
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    Online Resource
    Copernicus GmbH ; 2011
    In:  Atmospheric Chemistry and Physics Vol. 11, No. 8 ( 2011-04-27), p. 3835-3846
    In: Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 11, No. 8 ( 2011-04-27), p. 3835-3846
    Abstract: Abstract. Size-resolved and bulk activation properties of aerosols were measured at a regional/suburban site in the North China Plain (NCP), which is occasionally heavily polluted by anthropogenic aerosol particles and gases. A Cloud Condensation Nuclei (CCN) closure study is conducted with bulk CCN number concentration (NCCN) and calculated CCN number concentration based on the aerosol number size distribution and size-resolved activation properties. The observed CCN number concentration (NCCN-obs) are higher than those observed in other locations than China, with average NCCN-obs of roughly 2000, 3000, 6000, 10 000 and 13 000 cm−3 at supersaturations of 0.056, 0.083, 0.17, 0.35 and 0.70%, respectively. An inferred critical dry diameter (Dm) is calculated based on the NCCN-obs and aerosol number size distribution assuming homogeneous chemical composition. The inferred cut-off diameters are in the ranges of 190–280, 160–260, 95–180, 65–120 and 50–100 nm at supersaturations of 0.056, 0.083, 0.17, 0.35 and 0.7%, with their mean values 230.1, 198.4, 128.4, 86.4 and 69.2 nm, respectively. Size-resolved activation measurements show that most of the 300 nm particles are activated at the investigated supersaturations, while almost no particles of 30 nm are activated even at the highest supersaturation of 0.72%. The activation ratio increases with increasing supersaturation and particle size. The slopes of the activation curves for ambient aerosols are not as steep as those observed in calibrations with ammonium sulfate suggesting that the observed aerosols is an external mixture of more hygroscopic and hydrophobic particles. The calculated CCN number concentrations (NCCN-calc) based on the size-resolved activation ratio and aerosol number size distribution correlate well with the NCCN-obs, and show an average overestimation of 19%. Sensitivity studies of the CCN closure show that the NCCN at each supersaturation is well predicted with the campaign average of size-resolved activation curves. These results indicate that the aerosol number size distribution is critical in the prediction of possible CCN. The CCN number concentration can be reliably estimated using time-averaged, size-resolved activation efficiencies without accounting for the temporal variations.
    Type of Medium: Online Resource
    ISSN: 1680-7324
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2011
    detail.hit.zdb_id: 2092549-9
    detail.hit.zdb_id: 2069847-1
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  • 3
    In: Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 12, No. 5 ( 2012-03-02), p. 2381-2397
    Abstract: Abstract. In this paper, the mixing state of light absorbing carbonaceous (LAC) was investigated with a two-parameter aerosol optical model and in situ aerosol measurements at a regional site in the North China Plain (NCP). A closure study between the hemispheric backscattering fraction (HBF) measured by an integrating nephelometer and that calculated with a modified Mie model was conducted. A new method was proposed to retrieve the ratio of the externally mixed LAC mass to the total mass of LAC (rext-LAC) based on the assumption that the ambient aerosol particles were externally mixed and consisted of a pure LAC material and a core-shell morphology in which the core is LAC and the shell is a less absorbing material. A Monte Carlo simulation was applied to estimate the overall influences of input parameters of the algorithm to the retrieved rext-LAC. The diurnal variation of rext-LAC was analyzed and the PartMC-MOSAIC model was used to simulate the variation of the aerosol mixing state. Results show that, for internally mixed particles, the assumption of core-shell mixture is more appropriate than that of homogenous mixture which has been widely used in aerosol optical calculations. A significant diurnal pattern of the retrieved rext-LAC was found, with high values during the daytime and low values at night. The consistency between the retrieved rext-LAC and the model results indicates that the diurnal variation of LAC mixing state is mainly caused by the diurnal evolution of the mixing layer.
    Type of Medium: Online Resource
    ISSN: 1680-7324
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2012
    detail.hit.zdb_id: 2092549-9
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  • 4
    In: Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 11, No. 14 ( 2011-07-18), p. 6911-6929
    Abstract: Abstract. Size-resolved chemical compositions of non-refractory submicron aerosol were measured using an Aerodyne quadrupole aerosol mass spectrometer (Q-AMS) at the rural site Back Garden (BG), located ~50 km northwest of Guangzhou in July 2006. This paper characterized the submicron aerosol particles of regional air pollution in Pearl River Delta (PRD) in the southern China. Organics and sulfate dominated the submicron aerosol compositions, with average mass concentrations of 11.8 ± 8.4 μg m−3 and 13.5 ± 8.7 μg m−3, respectively. Unlike other air masses, the air masses originated from Southeast-South and passing through the PRD urban areas exhibited distinct bimodal size distribution characteristics for both organics and sulfate: the first mode peaked at vacuum aerodynamic diameters (Dva) ∼200 nm and the second mode occurred at Dva from 300–700 nm. With the information from AMS, it was found from this study that the first mode of organics in PRD regional air masses was contributed by both secondary organic aerosol formation and combustion-related emissions, which is different from most findings in other urban areas (first mode of organics primarily from combustion-related emissions). The analysis of AMS mass spectra data by positive matrix factorization (PMF) model identified three sources of submicron organic aerosol including hydrocarbon-like organic aerosol (HOA), low volatility oxygenated organic aerosol (LV-OOA) and semi-volatile oxygenated organic aerosol (SV-OOA). The strong correlation between HOA and EC indicated primary combustion emissions as the major source of HOA while a close correlation between SV-OOA and semi-volatile secondary species nitrate as well as between LV-OOA and nonvolatile secondary species sulfate suggested secondary aerosol formation as the major source of SV-OOA and LV-OOA at the BG site. However, LV-OOA was more aged than SV-OOA as its spectra was highly correlated with the reference spectra of fulvic acid, an indicator of aged and oxygenated aerosol. The origin of HOA and OOA (the sum of LV-OOA and SV-OOA) has been further confirmed by the statistics that primary organic carbon (POC) and secondary organic carbon (SOC), estimated by the EC tracer method, were closely correlated with HOA and OOA, respectively. The results of the EC tracer method and of the PMF model revealed that primary organic aerosol (POA) constituted ~34–47 % of OA mass and secondary organic aerosol (SOA) constituted ~53–66 % of regional organic aerosol in PRD during summer season. The presence of abundant SOA was consistent with water soluble organic carbon (WSOC) results (accounting for ~60 % of OC on average) by Miyazaki et al. (2009) for the same campaign. OOA correlated well with WSOC at the BG site, indicating that most OOA were water soluble. More specifically, approximately 86 % of LV-OOA and 61 % of SV-OOA were estimated as water soluble species on the basis of carbon content comparison.
    Type of Medium: Online Resource
    ISSN: 1680-7324
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2011
    detail.hit.zdb_id: 2092549-9
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  • 5
    In: Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 12, No. 11 ( 2012-06-06), p. 4935-4950
    Abstract: Abstract. Visibility degradation is a pervasive and urgent environmental problem in China. The occurrence of low visibility events is frequent in the North China Plain, where the aerosol loading is quite high and aerosols are strongly hygroscopic. A parameterization of light extinction (Kex) for low visibilities on hazy days is proposed in this paper, based on visibility, relative humidity (RH), aerosol hygroscopic growth factors and particle number size distributions measured during the Haze in China (HaChi) Project. Observational results show that a high aerosol volume concentration is responsible for low visibility at RH 〈90%; while for RH 〉90%, decrease of visibility is mainly influenced by the increase of RH. The parameterization of Kex is developed on the basis of aerosol volume concentrations and RH, taking into accounts the sensitivity of visibility to the two factors and the availability of corresponding data. The extinction coefficients calculated with the parameterization schemes agree well with the directly measured values.
    Type of Medium: Online Resource
    ISSN: 1680-7324
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2012
    detail.hit.zdb_id: 2092549-9
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  • 6
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    Copernicus GmbH ; 2022
    In:  The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences Vol. XLIII-B3-2022 ( 2022-05-30), p. 729-734
    In: The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Copernicus GmbH, Vol. XLIII-B3-2022 ( 2022-05-30), p. 729-734
    Abstract: Abstract. Arable land protection is essential for Zero hunger the Sustainable Development Goals of United Nations, and the arable land protection includes two aspects, non-farming and non-grain. We try to monitor the arable land protection in Zhejiang with domestic satellite imagery. Satellite remote technology has become an essential way to monitor the land cover change (for non-farming) and grain crops (for non-grain). However, current monitoring frequency and scale were unable to satisfy the needs for non-farming monitoring. The low-resolution image cannot satisfy the feature of land fragmentation of Zhejiang for non-grain monitoring. To address the above problem, this paper proposes a land cover change method to monitor non-farming purposes based on deeplabv3+ with monthly coverage 2 meters resolution images. By focusing on rebuilding training data set and improving training strategy with hard example training, the difficulty of the spurious change caused by the adjustment of farming structure is solved. At the same time, this paper builds three training processes (Initial training, Fine training, Retraining for promotion) based on Fully Convolutional Neural Network FCN-8S to monitor the main grain crops in Zhejiang. The phenological features are added into the process of training to further improve the accuracy. At present, land cover change method of this paper has been applied in Zhejiang province and the monitoring of grain crops has been carried out in some regions according to the specific requirements. The result shows that both the two methods exhibit good accuracy and generalization ability at the time and space scale.
    Type of Medium: Online Resource
    ISSN: 2194-9034
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2022
    detail.hit.zdb_id: 2874092-0
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  • 7
    Online Resource
    Online Resource
    Copernicus GmbH ; 2012
    In:  Atmospheric Chemistry and Physics Vol. 12, No. 4 ( 2012-02-17), p. 1811-1822
    In: Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 12, No. 4 ( 2012-02-17), p. 1811-1822
    Abstract: Abstract. Both organic carbon (OC) and elemental carbon (EC) were measured during PRIDE-PRD 2006 summer campaign by using a semi-continuous thermal-optical carbon analyzer at a rural site, Back Garden (BG), which is located 50 km to the northwest of Guangzhou City. Together with the online EC/OC analyzer, various kinds of instruments related to aerosol chemical properties were employed here, which provided a good opportunity to check data quality. The concentrations of OC correlated well with the mass of organic matter (OM) and water soluble organic carbon (WSOC), implying the reliability of the data measured in this campaign. The average OC concentrations in fine particle for three typical periods during the campaign (local emission influence, typhoon and precipitation and normal days) were 28.1 μgC m−3, 4.0 μgC m−3 and 5.7 μgC m−3, respectively; and EC were 11.6 μgC m−3, 1.8 μgC m−3, and 3.3 μgC m−3, respectively. The diurnal patterns of EC and OC during the campaign were higher at night and in early morning than daytime, which was probably caused by the primary emission and accumulation in the occurrence of low boundary layer. Compared with the constant diurnal enhancement ratios of EC, the enhancement ratio of OC (OC versus (CO-CObackground)) kept in a relative high level in the afternoon, with a similar diurnal profile to oxygenated organic aerosol (OOA), due to the strong photochemical formation of OC. Here, a modified EC tracer method was used to estimate the formation of secondary organic carbon (SOC). These results showed that the average SOC concentration (normal days) at BG site was about 2.0 ± 2.3 μgC m−3, and the SOC fraction in OC could reach up to 80% with the average of 47%. The modified approach in this study proved to be effective and reliable for SOC estimation based on good correlations between estimated SOC versus OOA or WSOC, and estimated POC versus hydrocarbon-like organic aerosol (HOA).
    Type of Medium: Online Resource
    ISSN: 1680-7324
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2012
    detail.hit.zdb_id: 2092549-9
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  • 8
    In: Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 11, No. 9 ( 2011-05-11), p. 4353-4369
    Abstract: Abstract. North China Plain (NCP) is one of the most densely populated regions in China and has experienced enormous economic growth in the past decades. Its regional trace gas pollution has also become one of the top environmental concerns in China. Measurements of surface trace gases, including O3, NOx, SO2 and CO were carried out within the HaChi (Haze in China) project at Wuqing Meteorology Station, located between 2 mega-cities (Beijing and Tianjin) in the NCP, from 9 July 2009 to 21 January 2010. Detailed statistical analyses were made in order to provide information on the levels of the measured air pollutants and their characteristics. Gaseous air pollutant concentrations were also studied together with meteorological data and satellite data to help us better understand the causes of the observed variations in the trace gases during the field campaign. In comparison to measurements from other rural and background stations in the NCP, relatively high concentrations were detected in Wuqing, presumably due to regional mixing and transport of pollutants. Local meteorology had deterministic impacts on air pollution levels, which have to be accounted for when evaluating other effects on pollutant concentrations. Trace gas concentrations showed strong dependence on wind, providing information on regional pollution characteristics. O3 mixing ratio also showed clear dependencies on temperature and relative humidity.
    Type of Medium: Online Resource
    ISSN: 1680-7324
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2011
    detail.hit.zdb_id: 2092549-9
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  • 9
    In: Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 11, No. 7 ( 2011-04-14), p. 3479-3494
    Abstract: Abstract. The hygroscopic properties of submicron aerosol particles were determined at a suburban site (Wuqing) in the North China Plain among a cluster of cities during the period 17 July to 12 August, 2009. A High Humidity Tandem Differential Mobility Analyser (HH-TDMA) instrument was applied to measure the hygroscopic growth factor (GF) at 90%, 95% and 98.5% relative humidity (RH) for particles with dry diameters between 50 and 250 nm. The probability distribution of GF (GF-PDF) averaged over the period shows a distinct bimodal pattern, namely, a dominant more-hygroscopic (MH) group and a smaller nearly-hydrophobic (NH) group. The MH group particles were highly hygroscopic, and their GF was relatively constant during the period with average values of 1.54 ± 0.02, 1.81 ± 0.04 and 2.45 ± 0.07 at 90%, 95% and 98.5% RH (D0 = 100 nm), respectively. The NH group particles grew very slightly when exposed to high RH, with GF values of 1.08 ± 0.02, 1.13 ± 0.06 and 1.24 ± 0.13 respectively at 90%, 95% and 98.5% RH (D0 = 100 nm). The hygroscopic growth behaviours at different RHs were well represented by a single-parameter Köhler model. Thus, the calculation of GF as a function of RH and dry diameter could be facilitated by an empirical parameterization of κ as function of dry diameter. A strong diurnal pattern in number fraction of different hygroscopic groups was observed. The average number fraction of NH particles during the day was about 8%, while during the nighttime fractions up to 20% were reached. Correspondingly, the state of mixing in terms of water uptake varied significantly during a day. Simulations using a particle-resolved aerosol box model (PartMC-MOSAIC) suggest that the diurnal variations of aerosol hygroscopicity and mixing state were mainly caused by the evolution of the atmospheric mixing layer. The shallow nocturnal boundary layer during the night facilitated the accumulation of freshly emitted carbonaceous particles (mainly hydrophobic) near the surface while in the morning turbulence entrained the more aged and more hygroscopic particles from aloft and diluted the NH particles near the surface resulting in a decrease in the fraction of NH particles.
    Type of Medium: Online Resource
    ISSN: 1680-7324
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2011
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  • 10
    Online Resource
    Online Resource
    Copernicus GmbH ; 2011
    In:  Atmospheric Chemistry and Physics Vol. 11, No. 14 ( 2011-07-25), p. 7319-7332
    In: Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 11, No. 14 ( 2011-07-25), p. 7319-7332
    Abstract: Abstract. PM2.5 and TSP samples were collected at the summit of Mountain Tai (MT) (1534 m a.s.l.) in spring 2006/2007 and summer 2006 to investigate the characteristics of aerosols over central eastern China. For comparison, aerosol samples were also collected at Tazhong, Urumqi, and Tianchi in Xinjiang in northwestern China, Duolun and Yulin in northern China, and two urban sites in the megacities, Beijing and Shanghai, in 2007. Daily mass concentrations of TSP and PM2.5 ranged from 39.6–287.6 μg m−3 and 17.2–235.7 μg m−3 respectively at the summit of MT. Averaged concentrations of PM2.5 showed a pronounced seasonal variation with higher concentration in summer than spring. 17 water-soluble ions (SO42−, NO3−, Cl−, F−, PO43−, NO2−, CH3COO−, CH2C2O42−, C2H4C2O42−, HCOO−, MSA, C2O42−, NH4+, Ca2+, K+, Mg2+, Na+), and 19 elements of all samples were measured. SO42−, NO3−, and NH4+ were the major water-soluble species in PM2.5, accounting for 61.50 % and 72.65 % of the total measured ions in spring and summer, respectively. The average ratio of PM2.5/TSP was 0.37(2006) and 0.49(2007) in spring, while up to 0.91 in summer, suggesting that aerosol particles were primarily comprised of fine particles in summer and of considerable coarse particles in spring. Crustal elements (e.g., Ca, Mg, Al, Fe, etc.) showed higher concentration in spring than summer, while most of the pollution species (SO42−, NO3−, K+, NO2−, NH4+, Cl−, organic acids, Pb, Zn, Cd, and Cr) from local/regional anthropogenic emissions or secondary formation presented higher concentration in summer. The ratio of Ca/Al suggested the impact of Asian dust from the western deserts on the air quality in this region. The high concentration of K+ in PM2.5 (4.41 μg m−3) and its good correlation with black carbon (r = 0.90) and oxalic acid (r = 0.87) suggested the severe pollution from biomass burning, which was proved to be a main source of fine particles over central eastern China in summer. The contribution of biomass burning to the fine particle at MT accounted for 7.56 % in spring and 36.71 % in summer, and even reached to 81.58 % on a day. As and Pb were two of the most enriched elements. The long-range transport of aerosols spread the heavy pollution from coal-mining/coal-ash to everywhere over China. Anthropogenic air-pollution was evidently rather severe at MT, though it has been declared by UNESCO to be a World Heritage site.
    Type of Medium: Online Resource
    ISSN: 1680-7324
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2011
    detail.hit.zdb_id: 2092549-9
    detail.hit.zdb_id: 2069847-1
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